High density pulsed power capacitors are useful in delivering high power electrical pulses with fast current rise times and short pulse duration. A series of pulses may be delivered to a load, which increases the capacitor temperature due to energy storage as each pulse is delivered. The rise in temperature is often additive as each pulse is delivered. Some applications, especially military ones, need pauses after every pulse and/or a series of pulses. A significant temperature restitution may be needed during these pauses to maintain optimal operation of the capacitor by preventing the degradation of the dielectric capability of the capacitor and also to enable the required mission. Thus, high temperatures and/or extended cool down periods are very undesirable. Some capacitors are comprised of a rolled winding having a polypropylene material forming the dielectric and that may be rated up to about 55 degrees Celsius, and have energy densities of between 2 J/cc and 3.5 J/cc. Certain constructions may include a bank of capacitors to allow 80,000 Amp output current for fast pulses in the 0.1 to 10 ms range for directed energy applications requiring a unit size of 50 kJ to 400 kJ/can. The down time of the capacitor during a cooling cycle may extend many hours due to the large time constant of the capacitor, creating an extended and undesired downtime.
Some capacitors may be liquid cooled. However, conventional liquid cooled capacitors have limited ability to remove sufficient heat or thermal energy from the capacitor, and extended downtimes of hours are still incurred along with unacceptably high dielectric temperatures in high-stress operational conditions.